1. Field of the Invention
The present invention relates to a gelatino silver halide photo-sensitive material, and more particularly, to a practical and useful gelatino silver halide photo-sensitive material containing a compound to effect both the sensitization, due to the increase of the covering power based on control of the hardening, and to prevent the formation of fog.
2. Description of the Prior Art
In the hitherto known production of such gelatino silver halide photo-sensitive material, there have been proposed a great variety of processes to increase the sensitivity and the gamma of the photo-sensitive material, for example, by adding a covering power-increasing agent, for example, natural or synthetic high molecular weight compounds, such as poly-N-vinylpyrrolidone, dextrin, laminarin, mannam, hydroxyethylated cellulose, and the like.
The addition of these compounds makes it possible to effect an increase in the ratio of the optical density of silver to the weight of silver, namely, covering power and increase of contrast.
Generally, the addition of a large quantity of high molecular weight compounds is required; however, this has the disadvantages that the time necessary for development is increased due to the increased thickness of the emulsion layer as well as the adverse effects on the physical strength of the gelatin underlayer.
A primary object of the present invention is to provide a silver halide photo-sensitive material with increased sensitivity, maximum density and contrast based on an increase in covering power.
It is another object of the present invention to provide a photo-sensitive material having a shorter developing time than that of known photo-sensitive materials containing a covering power-increasing agent while preventing a decrease of the physical strength of the gelatin layer.